It has generally been established that disordered flow in blood vessels can be detected using both sound and velocity measurements. Previous and ongoing investigations of the present authors have focused on the analysis of disturbed flow patterns created by subtotal vascular stenoses and mathematical data processing methods for recognizing this disorder have been developed. The hot film anemometer, because of its good response to high frequency velocity fluctuations, has been used to date for both in vivo and in vitro studies. However, it has limited application in humans because it is necessarily invasive and poses obvious dangers. For screening purposes to detect clinical vascular disease it is quite inappropriate. The pulsed ultrasonic Doppler velocimeter (PUDVM) overcomes the invasive limitations of the hot film system, but has not been sufficiently developed for turbulence measurement because of frequency response and spatial resolution limitations. The proposed work is directed at further development of the PUDVM for use in turbulence studies. The research is in two parts: (1) further refinement of a phase lock loop technique for detecting and converting the Doppler shift signal produced by disordered flow, (2) development of a digital signal processing system centered around our present minicomputer-based HP 5451B Fourier Analyzer. These will be supported by both theoretical and experimental research into the statistics and characteristics of the scattering volume. Major emphasis will be centered on topic (2) with the objective of developing a processing method for ascertaining the turbulent flow characteristics directly using the scattered signal from the sample volume. The problem of sampling function and instrument response function correction will be treated.